Things clicked for Maggie when she saw Meredith and Riggs making googly eyes at each other during a press conference celebrating their in-plane heroics and receiving a commendation from the Washington governor, weeks after they decided to make the relationship official following their traumatic experience.

Later, Meredith pulled Maggie into the hospital supply closet, profusely apologizing for keeping her in the dark about her romance with Riggs.

"I get it. There was a plane, emotions were heightened. You almost died together. I get it," Maggie said tersely. But little did she know, Meredith and Riggs had been going on for a while -- well before the plane, in fact. "Before Amelia and Owen's wedding," Meredith said, finally coming clean to her shocked half-sister.

"It started before I even knew you liked him and as soon as you told me you liked him, I called it off," she continued, which just added insult to injury as far as Maggie was concerned, who brought up their many conversations about her crush on Riggs.

But ultimately, it wasn't about Riggs; it was about Meredith keeping something this important from her.

"It's you. I trusted you to be honest with me when even my mother lied to me and now she's dead. I thought I could count on you to tell me the truth but you've been lying this whole time," Maggie said through tears. "Well, you didn't [do the right thing]."

"Can we just not leave it like this?" Meredith pleaded. "You were all I had left," a heartbroken Maggie said.

That evening, in an attempt at extending an olive branch, Meredith made strides to bring her sister back around, hoping a girls' night out with Amelia (Caterina Scorsone) would be a good first step.

"I am very sorry that I screwed up and hurt you, but you're my sister and I'm sure as hell not losing you over a guy," Meredith said.

Eventually, Maggie agreed to go out with Meredith and Amelia. "I'm still not talking to you. I'm only going to talk to Amelia," Maggie concluded, which Meredith was all but OK with. After all, blood is thicker than water!

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